Numerical Constants

Numbers in the x86 architecture can be integers or floating point. Integers can be signed or unsigned, with signed integers represented in two's complement representation. Floating-point numbers can be: single-precision floating-point; double-precision floating-point; and double-extended precision floating-point.

Integer Constants

Integers can be expressed in several bases:

• Decimal. Decimal integers begin with a non-zero digit followed by zero or more decimal digits (0–9).

• Binary. Binary integers begin with “0b” or “0B” followed by zero or more binary digits (0, 1).

• Octal. Octal integers begin with zero (0) followed by zero or more octal digits (0–7).

• Hexadecimal. Hexadecimal integers begin with “0x” or “0X” followed by one or more hexadecimal digits (0–9, A–F). Hexadecimal digits can be either uppercase or lowercase.

Floating Point Constants

Floating point constants have the following format:

• Sign (optional) – either plus (+) or minus (–)

• Integer (optional) – zero or more decimal digits (0–9)

• Fraction (optional) – decimal point (.) followed by zero or more decimal digits

• Exponent (optional) – the letter “e” or “E”, followed by an optional sign (plus or minus), followed by one or more decimal digits (0–9)

A valid floating point constant must have either an integer part or a fractional part.